low-voltage wide-range linear transconductor cell

ABSTRACT

An improved low-voltage, low-power, wide range, and linear Gm Cell is disclosed. In one embodiment, a method of linearizing output current with an input voltage using a Gm Cell includes receiving an input differential voltage by an emitter degenerated input stage and outputting a current including a linear part and a nonlinear part at signal output terminals Iout_P and Iout_M, converting the non-linear part of the output current to a voltage difference via a compression stage, converting the voltage difference to a linear output current by a linear voltage to current converter stage, outputting the linear output current using a current mirror output stage to the signal output terminals Iout_P and Iout_M, and summing the output currents of the emitter degenerated input stage and the current mirror output stage at the signal output terminals Iout_P and Iout_M to obtain a linear output current with the input differential voltage.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to integrated circuits, and more particularly relates to transconductor devices.

BACKGROUND OF THE INVENTION

Transconductance is often an important measure of performance parameters including, but not limited to, bandwidth, gain, and noise. Transconductance is an expression of the performance of certain electronic circuits, and traditionally refers to the ratio of output current to input voltage of a particular circuit, or mutual conductance. The term “transconductance” refers to herein as the control of an output current as a result of an input voltage.

In integrated circuits, it may be important for the transconductance, also generally referred to as Gm, of an electronic circuit to remain constant over one or more operating parameters as well as processing variations. The stability or robustness of transconductane of transistors may be an important design parameter, as it may be affected by many operation and processing conditions, such as temperature, carrier mobility, supply voltage, etc.

Transconductors, also generally referred to as Gm Cells, are typically important building blocks in any circuit design. Generally, transconductors are widely used in applications, such as Gm-C filters, Sigma-delta modulators, multipliers and so on. Also generally, in these applications, transconductors are key components that can limit a required dynamic range.

One conventional solution, i.e., a Gm Cell having the most wide linear operating range is shown in FIG. 1. The Gm Cell 100 shown in FIG. 1 includes an emitter degenerated input stage 110, a compression stage 120, a Caprio circuit 130, an emitter follower stage 140, and a current biasing circuit 150. It can be seen in FIG. 1 that the biasing current IB is taken from a proportion to absolute temperature (PTAT) current reference to stabilize the Gm of the Bipolar Junction Transistors (BJTs). Further as shown in FIG. 1, VB is taken from source voltage reference that is capable of outputting stable current. Also as shown in FIG. 1, the supply voltage AVDD is connected to some internal regulated stable voltage source for improved power supply rejection (PSR) performance.

However, it can be seen that the Gm Cell 100 shown in FIG. 1, can require a supply voltage of nearly 3V in order to keep every transistor in a linear region. This is because VB is at least 3*Vbe+Vce, sat, which is around 2.4 V. For example, if loading circuitry needs 0.6V to stay in a high impedance mode, then the supply voltage required can be 3V, which does not include the extra room that is required for an output swing. Therefore, it can be seen that the Gm Cell 100 shown in FIG. 1 can require a supply voltage of at least 3V and this can be difficult to provide as the supply voltages shrink.

SUMMARY OF THE INVENTION

A low-voltage, low-power, wide range, and linear transconductor cell is disclosed. According to an aspect of the subject matter, the Gm Cell includes an emitter degenerated input stage, a compression stage, a Caprio circuit, a current biasing circuit, and a current mirror output stage. The emitter degenerated input stage is formed by transistors Q1 and Q4 and resistors R1 and R2, receives an input differential voltage from signal input terminals VinP and VinM by the emitter degenerated input stage and outputs a current including a linear part and a nonlinear part at signal output terminals Iout_P and Iout_M.

The compression stage formed by the transistors Q2, Q3, Q9 and Q10 converts the non-linear part of the output current received from the emitter degenerated input stage to a voltage difference between emitters of the transistors Q9 and Q10. Then, the Caprio circuit formed by transistors Q5, Q8, Q11 and Q12 converts the voltage difference between the emitters of the transistors Q9 and Q10 to a linear output current. The current mirror output stage formed by transistors Q6 and Q7 outputs the linear output current to the signal output terminals Iout_P and Iout_M. In some embodiments, the linear output current through transistors Q5 and Q8 is mirrored out by the transistors Q6 and Q7. Further, the output currents of the emitter degenerated input stage and the Caprio circuit are summed at the signal output terminals Iout_P and Iout_M to obtain a linear output current with the input differential voltage. In some embodiments, the transistor Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15, and Q16 are of the same type of transistors. In addition, the transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15, and Q16 are CMOS transistors and/or bipolar transistors.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:

FIG. 1 illustrates a circuit diagram of a Gm Cell in the context of the invention.

FIG. 2 is a circuit diagram of a Gm Cell, according to an embodiment.

FIG. 3 is a graph illustrating Gm versus the differential input voltage obtained during the operation of the Gm Cells shown in FIGS. 1 and 2, according to an embodiment of the present invention.

FIG. 4 is a graph showing noise performance comparison of the Gm Cells shown in FIGS. 1 and 2, according to an embodiment.

Other features of the present embodiments will be apparent from the accompanying drawings and from the detailed description that follows.

DETAILED DESCRIPTION OF THE INVENTION

A novel technique for a low-voltage, low-power, wide-range, and linear Gm Cell is disclosed. In the following detailed description of the embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

The terms “transconductance” and “Gm” are used interchangeably throughout the document. Further, the terms “transconductor cell” and “Gm Cell” are used interchangeably throughout the document.

FIG. 1 illustrates a circuit diagram of a Gm Cell 100 in the context of the invention. Particularly, FIG. 1 illustrates an emitter degenerated input stage 110, a compression stage 120, a Caprio circuit 130, an emitter follower stage 140, and a current biasing circuit 150.

As shown in FIG. 1, the emitter degenerated input stage 110 is formed by transistors Q1, Q2 and resistors R1, R2, wherein R1=R2 and R1 and R2 can be selected, for example, such that R1=R2=1/(2*Gm), wherein Gm is the desired transconductance. Further, the compression stage 120 is formed by transistors Q3 and Q4. The compression stage 120 converts a nonlinear part of a current from the emitter degenerated input stage 110 into a voltage difference between the emitters of the transistors Q3 and Q4.

The Caprio circuit 130 is formed by transistor Q5, Q6, Q7, Q8 and resistors R3 and R4, where R3=R4=R1=R2. The Caprio circuit 130 converts the voltage difference between the emitters of the transistors Q3 and Q4 to a linear current that is superimposed on the emitter degenerated input stage 110, resulting in a linear output current over very wide range for the Gm Cell 100.

The emitter follower stage 140 is formed by transistors Q9 and Q10. The emitter follower stage shifts an input voltage at the same output voltage level for cascading connections. The current biasing circuit 150 is formed by transistors Q13, Q14, Q15, Q16, Q17, Q18 and resistors R5, R6, R7, R8, R9. As shown in FIG. 1, the Gm Cell 100 includes a capacitor C1 for bypassing.

As shown in FIG. 1, a biasing current IB is taken from a PTAT current reference to stabilize the transconductance (Gm) of Bipolar Junction Transistors (BJTs). Further as shown in FIG. 1, VB is taken from source voltage reference that is capable of outputting stable current. Also as shown in FIG. 1, the supply voltage AVDD is connected to some internal regulated stable voltage source for improved power supply rejection (PSR) performance.

In operation, the Gm Cell 100 requires a supply voltage of at least 3V in order to keep all the transistors in a linear region. The voltage VB coupled to the compression stage 120 requires at least 3*V_(be)+Vce,sat volts, which is around 2.4V. For example, if the loading circuitry needs 0.6V to stay in high-Z (Impedance) mode, then the supply voltage requires 3V, which does not include the extra room that is required for an output swing. Therefore, it can be seen that the Gm cell 100 shown in FIG. 1 can require a supply voltage of at least 3V and this can be difficult to provide as the supply voltages shrink.

FIG. 2 is a circuit diagram of a Gm Cell 200, according to an embodiment. Particularly, FIG. 2 illustrates an emitter degenerated input stage 210, a compression stage 220, a Caprio circuit 230, a current biasing circuit 240, and a current mirror output stage 250. The Caprio circuit 230 shown in FIG. 2 is one embodiment of a linear voltage to current converter stage.

As shown in FIG. 2, the Gm Cell 200 includes the emitter degenerated input stage 210 coupled to signal input terminals VinP and VinM and signal output terminals Iout_P and Iout_M. The emitter degenerated input stage 210 includes a first transistor Q1 and a fourth transistor Q4. The emitter degenerated input stage 210 also includes a first resistor R1 and a second resistor R2 having substantially equal resistance values. For example, let the emitter area of Q2 (AE2) is one-fourth of the emitter area of Q1 (AE1). For an input degeneration resistance of 10 KOhms, the correct degeneration resistance for Q2 is 40 KOhms, i.e., 10 KOhm in parallel with 40 KOhms (10 KOhm//40 KOhms) results in an equivalent total resistance of R1=R2=40 K//10 K=8 KOhms. Therefore, by using one 8 KOhms resistor instead of one 10 KOhm and one 40 KOhm resistor eliminates the matching concern and saves area.

Further as shown in FIG. 2, the Gm Cell 200 includes the Caprio circuit 230 coupled to a supply voltage terminal AVDD. The Caprio circuit 230 includes a fifth transistor Q5, an eighth transistor Q8, an eleventh transistor Q11 and a twelfth transistor Q12, and a third resistor R3 and a fourth resistor R4. In some embodiments, the resistors R1, R2, R3 and R4 have substantially equal resistance values.

The Gm Cell 200 also includes the compression stage 220 coupled to the supply voltage terminal AVDD, the signal input terminals VinP and VinM, and the Caprio circuit 230. The compression stage 220 includes a second transistor Q2, a third transistor Q3, a ninth transistor Q9 and a tenth transistor Q10.

Further, the Gm Cell 200 includes the current biasing circuit 240 coupled to the emitter degenerated input stage 210, the Caprio circuit 230, a supply voltage terminal AVSS and a current input terminal IB. The current biasing circuit 240 includes a fourteenth transistor Q14. Also, the current biasing circuit 240 includes a thirteenth transistor Q13, a fifteenth transistor Q15, and a sixteenth transistor Q16 and associated fifth resistor R5, a sixth resistor R6 and a seventh resistor R7, respectively.

In addition, the Gm Cell 200 includes the current mirror output stage 250 coupled to the signal output terminals Iout_P and Iout_M. The current mirror output stage 250 includes transistors Q6 and Q7.

As shown in FIG. 2, the current biasing circuit 240 further includes a capacitor C1 having an input and an output. The input of the capacitor C1 is coupled to the current input terminal IB and the output of the capacitor C1 is coupled to the supply voltage terminal AVSS. The fourteenth transistor Q14 includes a first electrode, a second electrode and a control electrode, in which the control electrode of the fourteenth transistor Q14 is coupled to the current input terminal IB, and the first electrode of the fourteenth transistor Q14 is coupled to the supply voltage terminal AVDD.

Further, each of the thirteenth, fifteenth and sixteenth transistors Q13, Q15 and Q16 includes an associated first electrode, second electrode and control electrode. In some embodiments, the second electrode of the fourteenth transistor Q14 is coupled to the control electrodes of the thirteenth transistor Q13, the fifteenth transistor Q15 and the sixteenth transistor Q16.

As shown in FIG. 2, each of the fifth, sixth and seventh resistors R5, R6 and R7 have an associated input and output. In these embodiments, the input of the fifth resistor R5 is coupled to the second electrode of the thirteenth transistor Q13, the input of the sixth resistor R6 is coupled to the second electrode of the fifteenth transistor Q15, the input of the seventh resistor R7 is coupled to the sixteenth transistor Q16 and the outputs of the resistors R5, R6, and R7 are coupled to the supply voltage terminal AVSS.

Further, each of the first transistor Q1 and the fourth transistor Q4 in the emitter degenerated input stage 210 has an associated input electrode, second electrode and control electrode, and each of the first resistor R1 and the second resistor R2 in the emitter degenerated input stage 210 has an associated input and output. As shown in FIG. 2, the control electrode of the first transistor Q1 is coupled to the signal input terminal VinP, the first electrode of the first transistor Q1 is coupled to the signal output terminal Iout_M, and the second electrode of the first transistor Q1 is coupled to the input of the first resistor R1. The control electrode of the fourth transistor Q4 is coupled to the signal input terminal VinM, the first electrode of the fourth transistor Q4 is coupled to the signal output terminal Iout_P, and the second electrode of the fourth transistor Q4 is coupled to the output of the second resistor R2, and the output the first resistor R1 is coupled to the input of the second resistor R2.

Further as shown in FIG. 2, each of the second transistor Q2, third transistor Q3, ninth transistor Q9 and tenth transistor Q10 of the compression stage 220 has a first electrode, a control electrode and a second electrode. The first electrode of the ninth transistor Q9 is coupled to the supply voltage terminal AVDD, the control electrode of the ninth transistor Q9 is coupled to the control electrode of the tenth transistor Q10, the output electrode of the ninth transistor Q9 is coupled to the input electrode of the second transistor Q2, the second electrode of the second transistor Q2 is coupled to the input of the first resistor R1, the first electrode of the tenth transistor Q10 is coupled to the supply voltage terminal AVDD, the second electrode of the tenth transistor Q10 is coupled to the first electrode of the third transistor Q3, the second electrode of the third transistor Q3 is coupled to the output of the second resistor R2, the output of the first resistor R1 is coupled to the input of the second resistor R2, and the control electrode of the transistors Q9 and Q10 are coupled to the supply voltage terminal AVDD.

Further as shown in FIG. 2, each of the fifth, sixth, seventh, eighth, eleventh, and twelfth transistors Q5, Q6, Q7, Q8, Q11 and Q12 has a first electrode, a control electrode and a second electrode and each of the third and fourth resistors R3 and R4 has an input and an output. The first electrode of the eleventh transistor Q11 is coupled to the supply voltage terminal AVDD, the control electrode of the eleventh transistor Q11 is coupled to the output electrode of the ninth transistor Q9 and the input electrode of the second transistor Q2, the second electrode of the eleventh transistor Q11 is coupled the first electrode of the fifth transistor Q5, the control electrode of the fifth transistor Q5 is coupled to the control electrode of the sixth transistor Q6, the second electrode of the fifth transistor Q5 is coupled to the input of the resistor R3, the first electrode of the sixth transistor Q6 is coupled to the signal output terminal Iout_M, and the second electrode of the sixth transistor is coupled to the input of the third resistor R3.

Further, the first electrode of the seventh transistor Q7 is coupled to the signal output terminal Iout_P, the control electrode of the seventh transistor is coupled to the control electrode of the eighth transistor Q8, the second electrode of the seventh transistor Q7 is coupled to the output of the fourth resistor R4, the first electrode of the eighth transistor Q8 is coupled to the second electrode of the twelfth transistor Q12 and the control electrode of the fifth transistor Q5, the second electrode of the eighth transistor Q8 is coupled to the output of the fourth resistor R4, the control electrode of the eighth transistor Q8 is further coupled to the first electrode of the fifth transistor Q5 and the second electrode of the eleventh transistor Q11, the first electrode of the twelfth transistor Q12 is coupled to the supply voltage terminal AVDD, the control electrode of the twelfth transistor Q12 is coupled to the second electrode of the tenth transistor Q10 and the first electrode of the third transistor Q3, and the output of the third resistor R3 is coupled to the input of the fourth resistor R4.

In some embodiments, the transistor Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15, and Q16 are of the same type of transistors. In addition, the transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15, and Q16 are CMOS transistors and/or bipolar transistors.

In operation, an input differential voltage from the signal input terminals VinP and VinM is received by the emitter degenerated input stage 210 and a current including a linear part and a nonlinear part is outputted at the signal output terminals Iout_P and Iout_M. The non-linear part of the output current received from the emitter degenerated input stage 210 is converted to a voltage difference between the emitters of the transistors Q9 and Q10 by the compression stage 220. Further, the voltage difference between the emitters of the transistor Q9 and Q10 is converted to a linear output current by the Caprio circuit 230.

In operation, the linear output current is outputted using the current mirror output stage 250 to the signal output terminals Iout_P and Iout_M. Finally, the output currents of the emitter degenerated input stage 210 and the Caprio circuit 230 are summed at the signal output terminals Iout_P and Iout_M to obtain a linear output current with the input differential voltage. In these embodiments, the linear output current through the transistors Q5 and Q6 is mirrored out by the transistors Q6 and Q7 and then superimposed on the emitter degenerated input stage 210, resulting in a linear current-voltage (I-V) conversion over very wide range of input voltage for the Gm Cell 200. In some embodiments, the emitter areas of the transistors Q1 (A_(E1)), Q2 (A_(E2)), Q3 (A_(E3)), Q4 (A_(E4)), Q5 (A_(E5)), Q6 (A_(E6)), Q7 (A_(E7)), and Q8 (A_(E8)) are sized such that A_(E1)/A_(E2)=A_(E4)/A_(E3)=A_(E6)/A_(E5)=A_(E7)/A_(E8). In some embodiments, the transistor Q9 and Q10 are of the same type. Further, the transistors Q9 and Q1 are CMOS transistors and/or bipolar transistors.

In accordance with the above described procedure, the Gm Cell 200 requires a supply voltage AVDD of about 3*V_(be)+V_(ce),sat, which is around 2.4V. In one embodiment, the input is directly biased at the same voltage level (AVDD) as the output voltage (e.g., VDD/2=2.4/2=1.2), thus getting rid of the input emitter follower. Hence, the Gm Cell 200 operates at a lower voltage.

In accordance with the above described embodiments, the Gm Cell 100 and the Gm Cell 200 are simulated with the same total biasing current (100 μA) for the same transconductance (50 μS). For example, for Gm Cell 100, the VB is biased at 2.5V and the supply voltage is 4V, whereas for the Gm Cell 200 (S-cell), the supply voltage is 2.4V.

FIG. 3 is a graph 300 illustrating transconductance (Gm) versus the differential input voltage obtained during the operation of the Gm cells 100 and 200 shown in FIGS. 1 and 2 respectively, according to an embodiment of the present invention. As shown in FIG. 3, curve 302 represents the Gm versus the differential input voltage for the Gm Cell 100 and curve 304 represents the Gm versus the differential input voltage for the Gm Cell 200. It is apparent that, the Gm Cell 200 maintains linearity over a wide range (1.2VPP) as illustrated by the curve 304 when compared to the curve 302.

FIG. 4 is a graph 400 showing noise performance comparison of the Gm Cells 100 and 200 shown in FIGS. 1 and 2, according to an embodiment. As shown in FIG. 4, a response curve 402 represents the noise performance for the Gm Cell 100 and a response curve 404 represents the noise performance for the Gm Cell 200. It can be apparent that, the Gm Cell 200 has a comparable noise performance when compared to the Gm Cell 100 as shown in FIG. 4.

In summary, the following observations can be made:

-   -   1) The Gm Cell 200 successfully maintains the linearity over the         wide-range (1.2VPP) as shown in FIG. 3.     -   2) The Gm Cell 200 has a comparable noise performance to the Gm         Cell 100.         Therefore, it can be concluded that, the Gm Cell 200 maintains         the dynamic range performance of the Gm Cell 100 while reducing         the supply voltage from 4V to 2.4V. Thus, the Gm cell 200 leads         to about 40% power saving. Further, it can be seen that the         above Gm Cell 200 do not require the input emitter follower,         shown in FIG. 1, as the input voltage can be directly biased at         the same voltage as the output voltage, for example,         VDD/2=2.4/2=1.2V.

Although the present embodiments have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. For example, the various devices, modules, analyzers, generators, etc. described herein may be enabled and operated using hardware circuitry (e.g., CMOS based logic circuitry), firmware, software and/or any combination of hardware, firmware, and/or software (e.g., embodied in a machine readable medium). For example, the various electrical structure and methods may be embodied using transistors, logic gates, and electrical circuits (e.g., application specific integrated ASIC circuitry). 

1. A Gm Cell, comprising: an emitter degenerated input stage coupled to signal input terminals VinP and VinM and signal output terminals Iout_P and Iout_M, wherein the emitter degenerated input stage includes a first transistor Q1 and a fourth transistor Q4, and wherein the emitter degenerated input stage further includes a first resistor R1 and a second resistor R2 having substantially equal resistance values; a Caprio circuit coupled to a supply voltage terminal AVDD, wherein the Caprio circuit includes a fifth transistor Q5, an eighth transistor Q8, an eleventh transistor Q11, and a twelfth transistor Q12, and a third resistor R3 and a fourth resistor R4, wherein the resistors R1, R2, R3 and R4 have substantially equal resistance values; a compression stage coupled to the supply voltage terminal AVDD, the signal input terminals VinP and VinM, and the Caprio circuit, wherein the compression stage includes a second transistor Q2, a third transistor Q3, a ninth transistor Q9 and a tenth transistor Q10; and a current biasing circuit coupled to the emitter degenerated input stage, the Caprio circuit, a supply voltage terminal AVSS and a current input terminal IB, wherein the current biasing circuit includes a fourteenth transistor Q14, wherein the current biasing circuit further includes a thirteenth transistor Q13, a fifteenth transistor Q15, and a sixteenth transistor Q16 and associated fifth resistor R5, a sixth resistor R6 and a seventh resistor R7, respectively.
 2. The Gm Cell of claim 1, wherein the current biasing circuit further comprises a capacitor C1 including an input and an output, wherein the input of the capacitor C1 is coupled to the current input terminal IB and the output of the capacitor is coupled to the supply voltage terminal AVSS, wherein the fourteenth transistor Q14 includes a first electrode, a second electrode and a control electrode, wherein the control electrode of the fourteenth transistor Q14 is coupled to the current input terminal IB, and wherein the first electrode of the fourteenth transistor Q14 is coupled to the supply voltage terminal AVDD.
 3. The Gm Cell of claim 2, wherein the thirteenth transistor Q13 includes a first electrode, a second electrode and a control electrode, the fifteenth transistor Q15 includes a first electrode, a second electrode, and a control electrode, and the sixteenth transistor Q16 includes a first electrode, a second electrode and a control electrode, wherein the second electrode of the fourteenth transistor Q14 is coupled to the control electrodes of the thirteenth transistor Q13, the fifteenth transistor Q15, and the sixteenth transistor Q16.
 4. The Gm Cell of claim 3, wherein the fifth resistor R5 has an input and an output, the sixth resistor R6 has an input and an output, and the seventh resistor R7 has an input and an output, wherein the input of the fifth resistor R5 is coupled to the second electrode of the thirteenth transistor Q13, wherein the input of the sixth resistor R6 is coupled to the second electrode of the fifteenth transistor Q15, wherein the input of the seventh resistor R7 is coupled to the sixteenth transistor Q16 and wherein the outputs of the resistors R5, R6, and R7 are coupled to the supply voltage terminal AVSS.
 5. The Gm Cell of claim 4, wherein each of the first transistor Q1 and the fourth transistor Q4 in the emitter degenerated input stage has an associated input electrode, a second electrode and a control electrode, wherein each of the first resistor R1 and the second resistor R2 in the emitter degenerated input stage has an associated input and an output, and wherein the control electrode of the first transistor Q1 is coupled to the signal input terminal VinP, the first electrode of the first transistor Q1 is coupled to the signal output terminal Iout_M, and the second electrode of the first transistor Q1 is coupled to the input of the first resistor R1, wherein the control electrode of the fourth transistor Q4 is coupled to the signal input terminal VinM, the first electrode of the fourth transistor Q4 is coupled to the signal output terminal Iout_P and the second electrode of the fourth transistor Q4 is coupled to the output of the second resistor R2, and wherein the output the first resistor R1 is coupled to the input of the second resistor R2.
 6. The Gm Cell of claim 5, wherein each of the second transistor Q2, third transistor Q3, ninth transistor Q9 and tenth transistor Q10 of the compression stage has a first electrode, a control electrode and a second electrode, wherein the first electrode of the ninth transistor Q9 is coupled to the supply voltage terminal AVDD, the control electrode of the ninth transistor Q9 is coupled to the control electrode of the tenth transistor Q10, the output electrode of the ninth transistor Q9 is coupled to the input electrode of the second transistor Q2, the second electrode of the second transistor Q2 is coupled to the input of the first resistor R1, the first electrode of the tenth transistor Q10 is coupled to the supply voltage terminal AVDD, the second electrode of the tenth transistor Q10 is coupled to the first electrode of the third transistor Q3, the second electrode of the third transistor Q3 is coupled to the output of the second resistor R2, the output of the first resistor R1 is coupled to the input of the second resistor R2, and the control electrode of the transistors Q9 and Q10 are coupled to the supply voltage terminal AVDD.
 7. The Gm Cell of claim 6, wherein each of the fifth, sixth, seventh, eighth, eleventh, and twelfth transistors Q5, Q6, Q7, Q8, Q11 and Q12 has a first electrode, a control electrode and a second electrode and each of the third and fourth resistors R3 and R4 has an input and an output, wherein the first electrode of the eleventh transistor Q11 is coupled to the supply voltage terminal AVDD, the control electrode of the eleventh transistor Q11 is coupled to the output electrode of the ninth transistor Q9 and the input electrode of the second transistor Q2, the second electrode of the eleventh transistor Q11 is coupled the first electrode of the fifth transistor Q5, the control electrode of the fifth transistor Q5 is coupled to the control electrode of the sixth transistor Q6, the second electrode of the fifth transistor Q5 is coupled to the input of the resistor R3, the first electrode of the sixth transistor Q6 is coupled to the signal output terminal Iout_M, the second electrode of the sixth transistor is coupled to the input of the third resistor R3, the first electrode of the seventh transistor Q7 is coupled to the signal output terminal Iout_P, the control electrode of the seventh transistor is coupled to the control electrode of the eighth transistor Q8, the second electrode of the seventh transistor Q7 is coupled to the output of the fourth resistor R4, the first electrode of the eighth transistor Q8 is coupled to the second electrode of the twelfth transistor Q12 and the control electrode of the fifth transistor Q5, the second electrode of the eighth transistor Q8 is coupled to the output of the fourth resistor R4, the control electrode of the eighth transistor is further coupled to the first electrode of the fifth transistor Q5 and the second electrode of the eleventh transistor Q11, the first electrode of the twelfth transistor Q12 is coupled to the supply voltage terminal AVDD, the control electrode of the twelfth transistor Q12 is coupled to the second electrode of the tenth transistor Q10 and the first electrode of the third transistor Q3, and the output of the third resistor R3 is coupled to the input of the fourth resistor R4.
 8. The Gm Cell of claim 1, wherein the transistor Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15, and Q16 are of the same type of transistors.
 9. The GM Cell of claim 1, wherein the transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15, and Q16 are selected from the group consisting of CMOS transistors and bipolar transistors.
 10. A method of linearizing output current with an input voltage using a Gm Cell, wherein the Gm Cell having an emitter degenerated input stage, a compression stage, a linear voltage to current converter stage, a current mirror output stage and a current biasing circuit, comprising: receiving an input differential voltage from signal input terminals VinP and VinM by the emitter degenerated input stage and outputting a current including a linear part and a nonlinear part at signal output terminals Iout_P and Iout_M; converting the non-linear part of the output current received from the emitter degenerated input stage to a voltage difference via the compression stage; converting the voltage difference to a linear output current via the linear voltage to current converter stage; outputting the linear output current using the current mirror output stage to the signal output terminals Iout_P and Iout_M; and summing the output currents of the emitter degenerated input stage and the current mirror output stage at the signal output terminals Iout_P and Iout_M to obtain a linear output current with the input differential voltage. 